Construction on a 3.5km stretch of the airport-Barasat Metro corridor has been stalled for months because of a stalemate between two central agencies over the functioning of the arm of a crane.
The airport authorities have raised objections to Metro Railway using a crane for the construction of the corridor till New Barrackpore. Officials at the airport said if safety clearance could not be granted for the use of the crane, the only option is to stall flights when the crane will be functional.
Officials at the airport said Metro Railway’s appeal for consent to use the crane and raise the height of the arm to 30 metres from the ground is pending with the Airports Authority of India (AAI) in Delhi.
“A technical committee will review the proposal and do a feasibility study on how to allow work without compromising on safety,” said an official.
“It is technically impossible to give safety clearance for such a height. So, probably the only option is to stop flight operations for the period when the crane will function,” said an official at the airport.
The crane will be used for the construction of the diaphragm wall of the underground tracks from the airport to New Barrackpore, off Jessore Road. The construction will be adjacent to the airport’s boundary wall, a Metro official said.
The crane will pick up pre-fabricated iron cages, raise them to a height of 30 metres above the ground and then lower them into the excavated pit below.
“When the crane’s arm is allowed to be raised to 30 metres, it can create safety hazards for flight operations, particularly landing of an aircraft on the northern end of the runway. However, we have to discuss and find a way out,” a senior official of the Kolkata airport said on Wednesday.
“The construction can be allowed during a particular time of the day when flight operations will be stalled,” he said.
The Metro authorities said construction work on the stretch had been stopped a
few months ago following objections from the airport authorities over the use of the crane.
“Two pilots had complained about the height of the crane while landing. Following that we asked the Metro authorities to stop using the crane,” said an airport official.
Another airport official said the Metro authorities had sought a no-objection certificate for the work in October last year. “They should have taken the clearance before starting work,” he said.
The official said that if the crane’s arm is raised to 30 metres, there might be problems in the functioning of communication, navigation and surveillance equipment in and around the airport.
“This can push the touchdown point, where the aircraft’s wheels touch the runway while landing, further. Already, because of Jessore Road, the touchdown point is 1,400 feet from the starting point of the main runway,” said an airport official.
“If the touchdown point is pushed further, because of the crane’s height, the space on the runway that the pilots will get to slow down will shrink further,” he said.
A Metro official said they need permission to use the crane for “a short duration”.
The work on the 3.54km stretch is stuck for months because of the impasse, said the official. “The men and machines are idling at the site,” he said.
The stretch till New Barrackpore is part of the airport-Barasat Metro line which has been delayed by many years.
The airport-Barasat project was commissioned in January 2011 but never got going because of land logjams. In 2013, the contractor, Larsen & Toubro, withdrew from the project on the ground that there was “no clear site in a substantial patch”.
In 2018, it was decided that the tracks would be constructed till New Barrackpore because there was no land hurdle till there. “Construction is being done in the cut-and-cover method, as was done when the north-south Metro line was built,” said an official.
